<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>常见布局2</title>

    <style type="text/css">
        #left{
            float:left; width:240px; height:500px; background:#0C9;
        }
        #right{
            float:right;width:240px;height:500px; background:#933;
        }
        #center{
            height:500px;background:#06C;
            text-align: center;
        }
    </style>
</head>
<body>
<div id="left">左边</div>
<div id="right">右边</div>
<div id="center">中间</div>
</body>
</html>